Austyboo ^_^ said:
Why is visual character design in particular so weak in anime?
1. Most anime series are based off manga series, and most manga artists are not amazing designers.
2. There is an emphasis on differentiating characters by costume design rather than physical appearance, because costumes are more recognisable and people like to cosplay them and cosplay is basically free advertising.
3. Manga artists tend to draw very similarly, especially those artists who never studied anything else. This gets compounded in anime because a lot of the animation companies will simplify artwork even further to make them easier to animate.
4. In Japan (and China) there is no taboo for copying people's work, and by extension nobody looks down on highly derivative works. The former is seen as a sign of respect and appreciation for the original, while the latter is like "Hey! More of the same stuff that I enjoy! Great!". Thus you get a series like idolmaster where direct parallels can be made between characters in other series. A cutesy female-dominated series is expected to have a rigid subset of character archetypes, and these archetypes also dominate their appearance to such a degree that even the eye shape and hairstyles vary little between them.
Naturally this bleeds into other works which fall outside the "cutesy cast of 14 year old girls" genre.
Also because I am exposed to so much anime by people posting on the internet, and I recognise a lot of the characters by osmosis alone, I don't think the character designs are really all that similar. Especially when compared to american superhero comics where artists are literally all trained in exactly the same way and a lot of them have no experience outside drawing superhero-built people, so the only way characters are defined is by their costumes. Look at Rob Liefeld's stuff for an extreme, godwin's-law-tier example.